Wiith one probe on the wire joining the two two channels and the other on the bolt securing the mains earth wire, I get a reading of 0.8 volts.
Wiring - transformer connected directly to mains input socket. Secondary wires of tranformer joined to 1mm diameter solid copper wires into rectifier bridge. 0.6mm diameter wires from bridge to chips.
I will try a larger cap value as suggested and see what changes.
Back on topic, for those who are very worried about binding posts insulation, (and then use uninsulated banana plugs, spades or forks
), there is a better option.
Some manufacturers, like Linn, Arcam and others use BFA plugs.
Yes, all insulated. male and female.
Here's an example:
http://www.stoneaudio.co.uk/stoneaudio/products/details.asp?product=611
Here's another one:
http://www.noteworthyaudio.co.uk/diy/page14.html
This, for me, is better than banana plugs, but unfortunately it's not a standard.
And it's a one-way solution: use this and only this.
), there is a better option.Some manufacturers, like Linn, Arcam and others use BFA plugs.
Yes, all insulated. male and female.
Here's an example:
http://www.stoneaudio.co.uk/stoneaudio/products/details.asp?product=611
Here's another one:
http://www.noteworthyaudio.co.uk/diy/page14.html
This, for me, is better than banana plugs, but unfortunately it's not a standard.
And it's a one-way solution: use this and only this.
I love those. I've used them in speakers that have been stomped on, tripped over, tugged at and generally abused, but there is no way in hell that they are ever going to become disconnected until you want them off. That makes very sure no one is going to be able to touch the output. And they make a very satisfying *click*OliverD said:Neutrik Speakon connectors are insulated and mechanically rugged. Also the contact resistance is quite low compared to other solutions
The subject of this thread is far too important to allow it to be buried in pages of talk about component choice.
The issue of binding posts was raised with regard to the safety question and now we have moved on to discussing other connectors.
I hate to think that people will come to this thread to learn how to build hi-fi safely, and then give up because they find pages and pages of OT subjects like choice of connector sockets/plugs.
Let's get back to the safety issue with binding posts and I will try to summarise. If I am wrong perhaps somebody can correct me.
There are two safety issues with loudspeaker binding posts on amplifiers.
The first is the fact that they are uninsulated and if they somehow got connected to mains voltages, could electrocute a user connecting their speakers to the amplifier.
The second is to do with the type of connector that they accept. If that connector has smallish round pins, somebody unknowledgeable could arguably insert those connectors into a mains socket and electrocute themselves.
As I remember it, that happened to a man in France and brought about the 'new' type of loudspeaker connection system that manufacturers like Arcam adopted.
Now, if we accept that both of these issues are a valid safety concern, then we should be using terminals with a plastic covering and which accept a 'pin' that cannot be plugged into a mains socket.
As correctly stated, the Neutrik speaker connectors (and Cliffcon 'copies') meet both the requirements.
And there are other types like the example below.
I don't know how these sound in relation to the Cardas binding posts or any other speaker connection but the point is, in the context of this thread about safety, sound quality is not the issue!
Mods - I hope you can weed out the OT posts in this thread as they will surely deter people reading right through these important safety issues!
The issue of binding posts was raised with regard to the safety question and now we have moved on to discussing other connectors.
I hate to think that people will come to this thread to learn how to build hi-fi safely, and then give up because they find pages and pages of OT subjects like choice of connector sockets/plugs.
Let's get back to the safety issue with binding posts and I will try to summarise. If I am wrong perhaps somebody can correct me.
There are two safety issues with loudspeaker binding posts on amplifiers.
The first is the fact that they are uninsulated and if they somehow got connected to mains voltages, could electrocute a user connecting their speakers to the amplifier.
The second is to do with the type of connector that they accept. If that connector has smallish round pins, somebody unknowledgeable could arguably insert those connectors into a mains socket and electrocute themselves.
As I remember it, that happened to a man in France and brought about the 'new' type of loudspeaker connection system that manufacturers like Arcam adopted.
Now, if we accept that both of these issues are a valid safety concern, then we should be using terminals with a plastic covering and which accept a 'pin' that cannot be plugged into a mains socket.
As correctly stated, the Neutrik speaker connectors (and Cliffcon 'copies') meet both the requirements.
An externally hosted image should be here but it was not working when we last tested it.
And there are other types like the example below.
An externally hosted image should be here but it was not working when we last tested it.
I don't know how these sound in relation to the Cardas binding posts or any other speaker connection but the point is, in the context of this thread about safety, sound quality is not the issue!
Mods - I hope you can weed out the OT posts in this thread as they will surely deter people reading right through these important safety issues!
Nuuk said:
The question is how can that happen?
And another question is: why isolated on the amp and nude banana plugs or speaker terminals?
The man will be electrocuted all the same.
Nuuk, some people take heavy drugs and there's not much you can do to stop them if they want fireworks inside the house.
Some ot these guys can connect a speaker to the mains.
Well, yes, it is unlikely, but it could happen. Remember Carlos, the GC is attracting many builders who have no previous experience and even the best of us can make stupid mistakes.
All of us who encourage others to build electronic equipment (and that's what we do when we post here that something sounds very good) take on a certain amount of responsibility for the consequences! That is why Franz has correctly instigated this thread and why I feel so strongly about keeping it on topic!
Look at the examples I posted above (that is why I posted pictures
). The plugs are insulated as well as the sockets!Casrlos, that's true but that is no excuse not to run a thread like this where the information is available to the other guys who don't want the 'fireworks'. The type you refer to will be unlikely to read this thread anyway but it doesn't make the thread any less important or desireable.
Nuuk said:
What does that have to do with isolated binding posts?
I'm all in favour of discussing electrical safety.
I should advise any person without any electronics skills:
Do not open. Electrical shock. This is what you see on commercial gear.
If people are making an amp, they are fiddling with dangerous things.
They are fiddling inside.
But if one needs to isolate the binding posts, then it's better not to use metal cases too.
About the plugs, I posted this a couple of pages ago:
http://www.diyaudio.com/forums/showthread.php?postid=481847#post481847
Please follow the two links on that post.
I could not agree more. But I guess it is like much of the rest of this forum - when you don't have a clue about electronics and electrical engineering you turn your attention to something else.
Now, lets take on the subject of insulated speaker connectors. If you build a very high power amplifier its going to be somewhat of an issue because you could encounter amp voltages >50 V. But then you are probably using Neutrik Speakons anyway.
But for most GC:s its not an issue. Mains voltage is the issue.
And to Carlos, although it is rare transformer primary->secondary shorts DO occur like Nuuk said.
One of the very best guards against this is a protective shield between the primary and secondary windings connected to protective earth (PE). Most quality toroids have this and you would probably want it anyway coz' it also acts as a shield for capacitively coupled mains noise to the secondary winding.
But if you for this reason want insulated speaker connections you are going to need fully insulated input connections too, because signal ground is connected to these too. The Neutrik line of XLR connectors offers this too.
But the attention is better spent on proper mains wiring, earthing and fusing. Like Nuuk said, we are dealing with people here that don't know Ohm's law and how to make proper measurements but mess around with mains voltage. That is a very dangerous combination since mains voltage is dangerous even to the most seasoned engineers.
For those who want to study this subject in more depth I can recommend the chapter on electrical safety in the famous book "Medical Instrumentation: Application and Design" by John G. Webster. You are not likely to find more stringent rules about electrical safety than in the med. instrumentation business. Not for the beginning DIY:er though who simply wants practical hints on proper wiring.
Cheers
/Magnus
Swedish Chef said:
That's exactly my oppinion.
I talked about a Conrad-Johnson amp that has around 350W RMS/8 ohms and it uses nude binding posts.
This discussion is useless.
Curiously, this thread started with this discussion instead of more important things, as you say.
I'm sorry, I don't agree on the necessity of isolated binding posts.
If mains goes to the binding posts, it will also certainly go to the (nude) RCA plugs too.
You should have a fuse, that's what I mean.
I can't imagine a properly rated fuse not blowing up with the scenarios you are talking about.
So what's the point?
Let's move on with electrical safety.
Much more important is to use a fuse on the primary of the trafo.
For those who make an amp and sell it to someone, it's important not to have serviceable parts inside.
Use isolated fuse holders, accessible from the outside of the case.
The amp should only be opened by a qualified person.
Any beginner who doesn't appreciate basic electrical safety should look here: http://www.ibiblio.org/obp/electricCircuits/DC/DC_3.html
It is the best online write up of the topic that I have read.
(Then they can come back and wade through this heap of posts looking for specifics)
It is the best online write up of the topic that I have read.
(Then they can come back and wade through this heap of posts looking for specifics)
Carlos, there are two aspects of safety involved here. The first applies to the building of the equipment, the second to the using of it.
This thread should be dealing with both, although if the amp is built correctly, and the user doesn't open the case, there shouldn't be a problem as regards the user's safety. But it is mainly concerning the safe buiding that we are concerend with here.
I'm not sure what the argument is here. I would have thought on a thread about safety, there would be no need or call for debate!
Nuuk said:I would have thought on a thread about safety, there would be no need or call for debate!
If no need for debate, then somebody post here the norms and that's it.
Done.
I'm sorry, but I'm always more concerned about mains voltage, isolating everything inside, using a correct fuse, proper wiring, than the speaker binding posts.
But that's me.
Anyway, I'm not a specialist in the norms matter, and I haven't seen anyone here yet.
In fact, I was indirectly called a non-specialist and not welcome here, as well as you, Nuuk.
I don't have to defend you, but I, from now on, will not post in this thread, although I will follow it because maby relevant information is posted here.
And if it does, I'll post to congratulate.
carlosfm said:
I agree with Carlos. We are talking diy gainclones, built for a personal use. I wouldn't expect anybody who manages to build such an amp, be so stupid and plug AC plug into speakers output.
It may be a different matter with commercial products, especially in Europen markets, but to me it seems like the main danger with non insulated binding posts is from high voltage that can be present at the output, produced by such an amp.
The only touchable parts of an RCA (when plugged in) can be earthed. That makes it unlikely to pose a danger (as long as you have fuses, a RCD or whatever).carlosfm said:
You can never be sure that you will be the only one with access to your equipment. You can't really keep your amps locked away, and unexpected things like (gag) visiting children or idiots do happen. I would much prefer to overengineer my stuff and not need it than see someone turned into a tasty barbecued snack.Peter Daniel said:
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